There is likely a wealth of evidence we are not yet privy to, but from what we know already: (1) no one else present at the house during the commission of the murders (per cameras and his confession), (2) he confessed to killing SW (per his confession), (3) he IMMEDIATELY launched into a detailed plan to cover up that any murders took place, showing consciousness of guilt, including but not limited to: transporting the bodies and dumping them in tanks of crude oil and a shallow grave at his employer's site (committing multiple felonies in the process and hampering future investigation of their deaths by tampering with evidence), texting/calling his dead wife to pretend he did not know where she was, lying to police, family, friends, and the sympathetic public - launching a frantic search for said family while he knew they were dead, and giving multiple media interviews which most people found to lack grief, remorse, devastation, and appeared rehearsed with lies, and (4) only confessed to one murder and the felonies of tampering with evidence when police had zeroed in on the location of the bodies in one of the only possible explanations one could come up with to mitigate culpability. Am I missing anything? Well, that and his confession lacks a story that people could actually relate to and see a reasonable person actually behaving in the ways he claimed.